7 


I 


o 


Circular  No.  87. 


L.  O.  HOWAHI) 


I  oited  States  Department  •»!'  Auriailiure, 

BUREAU   Ol  IMOLOGY, 

Bntoaiknfrikt  uiu!  Cl.icf  of  Buredli  ^ 

— W— 

I  I  I.K. 


THE  <  oi.oitvno  i'(»i  no  itci  i  1.1 

i  /  .  ptinot  a  -■/  det 

Bj    1       II     i  "ii :  i  n  mu  \ 

BntomologUt  in  Cha  rp<  rinu  n  I 

There  are  feu  more  familiar  insects  to  the  farmer  and  others  who 
lead  a  rural  life  than  is  the  Colorado  potato  beetle,  or  "  potato  bug," 
as  ii  i-  commonly  known;   and  yet  scarcely  more  than  fortj    years 

■  the  potato  crop  of  the  United  States  had  no  very  important  insecl 
enemy.  Not  man;  years  later  this  insecl  had,  by  it-  depredations  on 
potato, •  of  our  most  valuable  food  staples,  caused  as  great  concern 

have  the  San  Jose  scale  and  cotton  boll  weevil  in  the  past  decade, 
and  was  also  the  subject  of  much  study  and  experiment.     Although 

common  an  insect, 
many    are    not    thor- 
o  ii  g  Ii  1  y    acquainted 
with    its    life   history 
and   habits  and   with 
ih«'    best    methods    of 
combating  it.  and  this 
applies  particularly  t<> 
persons     farming     in 
districts  only  recently 
invaded  by  the   foe.     The  insect   is  continually  extending  it-  range 
southward,  ami  many  complaint-  are  received  from  localities  where 
the  pest  has  not  become  thoroughly  acclimated. 

The   potato   beetle,   notwithstanding  all    that    has   been    don-   i. 
suppress  it.  is  -till  a  pest  of  great  importance.     It  i-  interesting  as 
the  first  known  example  of  an  insect  native  to  our  Western  States 
being  introduced  eastward  and  thence  practically  all  ovei  mtry 

and  Canada  (except  on  the  Pacific  ci  here  potato.-  aiv  grown. 

In  its  early  day-  a-  a  migrant  there  seemed  to  have  i n  no  check  to  its 

eastward  spread  other  than  natural  barriers,  such  as  rivers  and  lake* 
and  the  Atlantic  Ocean,  hut  iii  the  course  of  years  numbers  of  nat- 
ural en. 'mi.-     birds,  mammals,  and  predaton  and-parasitic  insects 

kn..\\!i  as     i 
■      87     07 


Kl..     1 


;;TO£\ 


have  learned  to  attack  it.  and.  in  the  case  of  the  insects,  they  have 
multiplied  until  now  they  are  recognized  as  important  factors  in 
the  control  of  the  beetle.     The  species  is  interesting  also  as  having 

led  to  the  first  use  of  an  arsenical  insecticide.  Paris  green,  on  edible 
plants.     Fortunately,  with  a  knowledge  of  the  habits  of  this  insect, 


> 


Fig.  2. — Section  of  potato  plant  showing  Colorado  potato  beetle  al  work:  a.  Rootle;  6,6, 
egg  masses  ;  cy\  half-grown  larva" :  ti.il.  mature  larvae.     Somewhat  enlarged  (original). 

the  use  of  arsenicals,  and  the  friendly  assistance  of  natural  enemies, 
the  grower  may  hold  it  in  practical  subjection. 

DESCRIPTIVE. 

The  Colorado  potato  beetle  is  so  well   known  that   a   description 
seems  hardly  necessary  for  most  persons,  but  that  there  may  be  no 
[Clr.  s7] 


in  "old-faali 
trior's  [11  US  I 


r  of  confusing  it   with  am    related   3pecies  or  with  benel 
ladybirds,  n  fvw  words  of  description  maj  be  given. 

Thebeeth  (fig.  1,  a;  fig.  2,  i)  i  of  robusl  form,  about  three-eighths 
of  mii  inch  in  length  or  a  little  more,  and  two  thirds  as  wide  as  long. 
Ii  i-  ochreous  vellov*  in  color,  and  the  wing-covers  are  ornamented 
with  ifii  longitudinal  black  lines.  The  Read  is  marked  with  :i 
triangular  black  spot,  and  the  thorax  is  dotted  with  ten  or  more 
irregular  spots  and  other  markings.  The  lower  surface  is  also  more 
or  If—  marked  with  black,  particularly  the  tarsi 
iintl  knees. 

/'/,-  larva  (fig.  !.  b;  fig.  2,  .  .  d,d)  are  quite  as 
well  known  as  (lit-  beetles  and  are  very  commonh 
called  "slugs."  They  are  dark  Venetian  red 
when  firsl  hatched,  and  as  they  approach  maturity 
become  paler.  They  are  -limy,  disgusting  looking 
creatures,  sofl  in  texture,  and  from  their  peculiar 
coloration  and  appearance  would  no!  be  readily 
handled  by  anyone  withoul  glovi 

The  pupa  is  red  like  the  larva  and  look-  as 
shown  in  ' .  figure  1 . 

The  eggs  i  fig.  •_'.  I>J>)  are  orange  colored  and  are 
deposited  in  masses. 

As  this  beetle  is  sometimes  confused  with  one  <>r 
another   of   the   "old-fashioned    potato   bugs"    (blister   beetles),   a 
species  of  the  latter  is  illustrated  here  for  comparison  i  fig.  3)-. 

ORIGIN   AND   DISTRIBUTION. 

It  has  always  been  believed     and,  the  writer  maintains,  with  rea- 
son, until  the  contrary   can  be  proved  beyond  doubt     tli.n  the  Colo- 
rack)  potato  beetle,  having  become  dispersed  from  ( Colorado  ;i-  a  starl 
ing  point,  originated  as  a  species  in  thai  region.     Dr.  W.  L  Tower, 
however,  in  a  publication  issued  in  L906,"  has  assumed  thai  this  insect 
had  the  same  origin  as  its  principal  wild  food  plant.  Solatium  n 
/>////,  which  he  states  is  essentially  tropical,  and  thai  the  inseel  has 
followed  the  distribution  of  the  plant  from  Mexico  into  Texas,  New 
co,  and  part-  of  Arizona.     He  also  gives  reasons  for  the  belief 
that  Leptinotarsa  decemlineata  has  developed  from  /..  "  intermedia 
Tower"  after  changing   it-   habitat,   the   latter  occurring   in    both 
■o  and  Texas,  and  the  former  not  being  found  in  Mexico  at  all. 
rding  to  his  experience. 

tUSTOBI    01     I  III'   I  \-i '<   I  '-  8PR]   \l>. 

The  eastward  dispersal  of  this  potato  beetle  from  what  is  generally 
considered  in  original  home  in  the  West  is  of  peculiar  interest     The 

\     Investigation  ot  Evolution  in  Clirysomelld  beetles  of  the  Genus  Leptl- 
Dotaraa,  Carnegie  institution.  Washington,  i>.  C  pp.  23  el  Beq. 

[fir.  87] 


beetle  appears  to  have  been  first  associated  with  injury  to  potato  in 
1865.  Forty-five  years  prior  to  that  time  it  had  been  recognized  as 
feeding  on  the  sand  bur,  or  beaked  nightshade  (Solanum  rostrat 
Dunal.),  a  related  solanaceous  plant  peculiar  to  the  Rocky  Mountain 
region.  The  beetle  was  described  in  1824  by  Thomas  Say.  With 
the  advance  of  civilization  westward  and  the  Cultivation  of  potato  in 
the  vicinity  of  its  native  home,  the  insect  acquired  the  habit  of  feed- 
ing upon  tin-  more  succulent  plant,  and  about  1859  it  had  spread  to 
the  east  as  far  as  Nebraska.  Two  years  afterwards  it  reached  Kansas, 
and  later  Iowa,  which  it  traversed  in  three  or  four  year-:  so  that  by 
1864  or  lMu  it  had  crossed  the  Mississippi  River  and  invaded  the 
western  borders  of  Illinois.  In  its  spread  through  Illinois  it  was  de- 
scribed by  Walsh  as  marching  through  that  Stale  "  in  many  separate 
columns,  just  as  Sherman  inarched  to  the  sea  ;  the  southern  columns  of 
the  grand  army  lagged  far  behind  the  northern  columns."  By  18G9 
it  had  found  its  way  to  Ohio,  appearing  almost  simultaneously  in  the 
northern  and  western  portions.  During  all  this  time,  beginning  with 
the  year  1861,  the  insect  had  done  considerable  injury,  and  by  1870  it 
had  become  exceedingly  destructive  in  the  North  and  Middle  West, 
and  was  continuing  its  eastward  inarch  at  an  increasing  rate.  It 
had  now  reached  the  Province  of  Ontario.  By  1872  its  depreda- 
tions in  the  West  had  noticeably  abated,  owing  to  the  effectiveness  of 
natural  enemies  and  to  the  increasing  use  of  Paris  green.. _  Its  prog- 
ress  eastward,  however,  continued,  the  northern  columns  becoming 
established  in  Pennsylvania  and  New  York,  the  southern  ones  reach- 
ing Kentucky.  The  next  year  it  made  its  first  appearance  in  the  Dis- 
trict of  Columbia  and  West  Virginia,  and  in  187-1  it  had  reached 
the  Atlantic  seaboard  and  was  reported  from  Connecticut  to  Mary- 
land and  Virginia. 

By  the  centennial  year  (1870)  the  Colorado  potato  beetle  had 
spread  over  an  area  composing  more  than  a  third  of  the  United 
States,  so  that  it  occupied  at  that  time  more  or  less  completely  the 
States  of  Colorado.  Nebraska.  Kansas.  Minnesota.  Iowa.  Missouri. 
Wisconsin.  Illinois.  Michigan.  Indiana.  Ohio.  Kentucky,  the  New  Eng- 
land States.  New  York.  New  Jersey.  Pennsylvania.  Delaware.  Mary- 
land. Virginia,  and  West  Virginia,  and  the  District  of  Columbia,  in 
none  of  which  was  it  native  except  in  the  State  first  mentioned.  At 
that  time  it  occupied  also  portions  of  Wyoming  and  southern 
Dakota — where  it  was  perhaps  also  native — and  a  considerable  part 
of  the  more  arable  portions  of  eastern  Canada. 

The  farther  spread  of  this  insect,  particularly  southward,  is  of  less 
interest  and  has,  in  many  instances  ar  least,  been  dependent  more  or 
less  on  the  increased  cultivation  of  the  potato.  The  following  addi- 
tional   statements   as   to   the   insect's  progress   are    taken    from   data 

[Clr.  87] 


collated  mainly  from  the  Records  of  this  office,  some  of  which 
are  published  more  in  detail  l>\  Tower.*  In  1-77  the  beetle  ap 
peared  in  North  Carolina  and  Tennessee,  The  following  year  il 
was  reported  to  be  completely  overrunning  portions  of  Canada, 
being  found  eastward  in  New  Brunswick.  In  ls~'.>  it  \\a-  recorded 
from  Manitoba.  In  1880  its  presence  was  observed  in  Texas.  Since 
about  lsv'-'  complaints  of  injuries  have  been  made  in  Nova  Scotia; 
in  L885,  at  Savannah,  Ga.;  in  L888,  at  Jackson,  Miss.;  and  in 
Smith  Count;.  Tex.  In  1892  the  species  had  become  abundant  in 
Alahama.  and  was  noticed  also  in  South  Carolina.  The  following 
year  its  occurrence  was  observed  by  H.  G,  Hubbard  at  Fort  A--iuni 
boine,  Mont.,  which  is  evidently  the  most  northern  limit  of  it-  original 
babitat,  as  it  was  not  found  there  on  potato.  In  succeeding  Mar- 
other  localities  were  added  in  soi f  the  State-  which  have  Ween 

mentioned,  but   little  of  positive  interest   adding  to  it-  known  dis 
tribution  has  been  learned  gince  1893.     It  should  be  stated,  however, 
that   the  species  ha--  heen   found  at   Jacksonville,   Ida.:  in  southern 
Louisiana,  and  at  San  Antonio.  Tex.,  hut  these  extreme  localities  do 
not  indicate  permanent  local  ion. 

PRESENT    DI8TRIB1    HON. 

The  natural  spread  of  the  potato  beetle  southward  increases  from 
time  to  time,  a-  evidenced  by  reports  that  reach  this  Department 
yearly.  Undoubtedly,  however,  the  extreme  northern  and  southern 
territories  which  it  invades  do  not  become  permanent  habitats  for  the 
insect,  the  species  dying  out.  mainly  because  of  extremes  of  cold  in 
the  one  case  and  of  heat  in  the  other,  to  he  reintroduced  in  later  years 
when  condition-  favor  it-  multiplication  and  spread  from  other 
regions. 

It  ha-  been  calculated  that  it  increased  it-  range  from  it-  original 
home  to  the  Atlantic  coa.-t  at  an  average  annual  rate  of  about  ^s 
mile-.  It-  spread  eastward  was  accomplished  largely  by  flight,  as 
the  writer  had  occasion  to  observe  when  a  resident  of  Cleveland  in 
the  early  day-  of  it-  invasion  of  northern  Ohio.  Great  numbers  of 
beetles  were  seen  on  bright  day-  in  spring  and  early  summer,  with 
outspread  win":-,  being  carried  directly  eastward  by  the  wind-. 

It  ha-  al-o  heen  disseminated  largely  by  railroads  and  by  lake 
vessels,  and  ha-  thu-  been  able,  through  the  direct  agency  of  man.  to 
cross  the  more  barren  plain-  bordering  it-  native  confines  and  the 
harriers  made  by  large  bodies  of  water.  So  it  will  he  seen  that  the 
wind-  and  waters  and  eastbound  train-  have  all  aided  in  it-  dis- 
semination eastward.  Riley,  from  whose  work-  the  present  account 
of  the  early  distribution  of  the  insect  ha-  been  taken,  observed  the 

'  I..  <■..  pp.  ::•• 
[Clr.  -Ti 


beetles  on  Lake  Erie  in  1870  on  various  floating  objects,  and  the 
writer  in  subsequent  years  saw  the  border-  of  the  same  lake  lined  for 
a  foot  and  more  with  the  hordes  of  these  hectics  thai  had  been  blown 
into  the  water  and  had  then  been  cast  up  on  the  shore. 

Beginning  with  about  1880,  it  will  be  noticed,  the  Colorado  hoetle 
appeared  in  many  potato  fields  of  the  Gulf  region  and  elsewhere  in 
the  South.  In  certain  localities,  particularly  in  Alabama  (where  it 
was  quite  injurious  for  a  time)  and  South  Carolina.  thi>  insect  seems 
to  have  disappeared,  and  little  danger  of  continuous  injury  need  be 
anticipated  there,  as  invasions  of  extreme  Lower  Austral  territory 
have  thus  far  been  merely  sporadic  appearances.  Still,  whenever 
atmospheric  conditions  favor,  the  species  docs  temporary  damage  in 
such  places,  only  to  he  killed  down  again  for  a  number  of  years,  after 
which  the  beetles  reappear,  sometimes  invading  new  localities.  It 
thus  will  be  seen  that  it  would  be  a  somewhat  difficult  task  to  outline 
definitely  the  permanent  distribution  of  this  insect.  It  is  nearly 
limited,  however,  as  regards  severe  injuries  to  the  country  east  of 
the  Rocky  Mountains,  extending  from  the  Lower  Austral  to  the 
Transition  life  zone,  and  is  likely  any  year  to  be  injurious  in  extreme 
portions  of  this  area. 

Injuries  by  this  species  in  the  potato  section  of  Aroostook  County 
in  northern  Maine  are  well  known,  and  the  region  there,  as  well  as  arc 
portions  of  Colorado,  is  credited  to  the  Boreal  life  zone."  From  recent 
reports  it  is  fair  to  say  that  the  species  is  scarcely  a  pest  at  the  pres- 
ent day  in  its  original  habitat  nor  in  neighboring  States,  since  (luring 
the  last  five  years  no  reports  of  extensive  injuries  have  been  received 
from  Colorado,  Kansas.''  Nebraska,  or  South  Dakota.  It  appears  to 
be  firmly  established,  however,  in  the  State-  just  west  of  the  Mis-;>- 
sippi  River  and  from  there  eastward  to  Nova  Scotia  and  New  Bruns- 
wick and  southward  to  the  northern  portions  of  the  Gulf  States. 

DISTRIBUTION    LIMITED    BY    EXTREMES    OF    TEMPERATURE. 

Some  of  the  conditions  which  prevent  the  too  rapid  multiplication 
and  permanent  establishment  of  the  potato  beetle  are  known.  At  St. 
Louis,  Mo.,  is  was  noticed  by  Riley  that  during  very  hot.  dry  weather, 
as  in  18G8,  this  insect  failed  to  go  through  its  transformations  in  the 
ground,  the  latter  becoming  so  hot  and  baked  that  the  pupae  dried 
out,  and  the  beetle,  if  it  succeeded  in  throwing  off  the  pupal  skin, 
failed  to  make  its  way  to  the  surface.  It  was  also  noticed  that  the 
larvae  frequently  perished  under  the  broiling  sun  when  the  ther- 

o These  regions  may  in  time  lie  recognized  as  lying  within  the  Transition  zone. 

&  Report  from  Mr.  Warren  Knaus,  dated  May  18,  1907,  states  that  this  insect 
lias  appeared  in  great  numbers  in  Kansas  and  threatens  serious  damage  to  young 
crops. 

[CIr.  stj 


mometer  ranged  near  100    I'.    During  the  intense  heal  thai  prevailed 
during  the  summer  of  1890  the  writer  noticed  the  same  condition    in 
and  near  the  District  of  Columbia,  the  eggs  and  larvae  being  literally 
dried  up  on  the  potato  plants,  and  the   species  temporarily  disap 
pearing  altogether. 

Northward   the   Colorado   potato  beetle   is   practically    limited   to 
the   Transition    zone,   although    it    occasionally    invades    the    B 
■one,  as,   for  example,  in  Colorado,  when    ii   has  been   found  B,000 
or  more  feet  above  sea  level.     Severe  winter  weather  alone  probably 
has  little  effed  upon  the  insect,  since  it  hibernal  i  rule,  exclu- 

sively in  the  beetle  state  and  deep  in  the  ground.  It  is,  moreover, 
one  of  our  most  hardy  species,  ranking  with  the  hard  shelled  snout- 
beetles  in  it-  resistance  t<>  cold  and  frost.  Cold  snaps,  however,  over 
take  the  insect  before  it  has  sought  < " h  proper  hibernating  quarters, 
iiikI  when  these  occur  it  is  doubtless  killed  ofl  in  great  numbers.  As 
was  predicted  years  ago,  the  Rocky  Mountains  have  proved  an 
impassable  barrier  for  tin-  species,  and  the  insect  has  not  been  able  to 
reach  the  Pacific  coast  or  neighboring  States  weal  of  such  barrier. 

INJURIES.    LIFE    HISTORY,    AND   HABITS. 
\  All   RE    OF    IN.il  RY. 

A  few  remarks  in  regard  to  the  nature  of  the  injury  inflicted  by 
this  insect  are  pertinent.  Beetles  and  larva;  are  destructive  in  nearly 
equal  proportions.  In  times  of  it-  earlj  occurrence  east  of  ii-  origi- 
nal limit  this  insect  not  only  caused  the  entire  1"--  of  crops,  but  some- 
times destroyed  the  potato  yield  of  whole  counties  and  of  large  por- 
tion- of  some  State-.  Indeed,  at  one  time  it  materially  affected  the 
market  price  of  potatoes,  not  alone  by  reason  of  it-  direci  depreda- 
tion-. l>nt  in  discouraging  farmers  from  the  cultivation  of  the  potato 
on  an  extensive  scale.  Thus  in  L873  the  price  per  bushel  at  whole- 
sale in  the  >t.  Louis  market  reached  the  high  figure  of  $2.  At  the 
present  time,  fortunately,  every  progressive  grower  recognizes  the 
fad  that  the  control  of  tin-  species  i-  a  part  of  the  necessary  routine 
connected  with  the  culture  of  tin-  tuber. 

It  was  early  recognized  that  the  depredation-  of  this  insect  ma- 
terially affected  the  quality  of  the  tuber  through  the  defoliation  to 
which  the  vines  were  subjected,  and  it  was  at  one  time  difficult  to 
obtain  potatoe-  that  were  not  watery  when  cooked.  This  raises  the 
question  whether  the  very  marked  decrease  in  quality  of  potatoes  in 
genera]  at  the  present  day  i-  not  due  directly  to  the  many  years  in 
which  the  tubers  have  been  deprived  of  due  nourishment  by  more  or 
less  defoliation  of  the  plant  it-elf:  for.  despite  all  the  remedial 
measures  that  are  usually  practiced,  such  a-  the  libera]  use  of  arsen- 
icals  and  "bugging"  or  jarring,  a  certain  amount  of  injury  nearly 
[Cli 


8 

always  takes  place,  which  can  not  fail  to  affect  the  tubers  when  it  has 
occurred  practically  without  interniittence  for  periods  of  from  twenty 
to  forty  years. 

food   PLANTS. 

A  wild  species  of  Solatium  (rostratum,  and  perhaps  also  coraw^m) 
is  an  original  food  plant  of  this  potato  beetle,  and  the  latter  is  proba- 
bly incapable  of  developing  for  any  number  of  generations  on  plants 
other  than  those  of  the  potato  or  nightshade  family  (Solanaceae). 
The  genus  Solatium  is  preferred,  and  the  potato,  because  of  its  greater 
succulence  and  less  acrid  taste,  is  now  chosen  in  preference  to  plants 
that  grow  wild.  Still,  the  insect  is  nearly  always  found  where  it- 
wild  food  plants  grow,  particularly  where  poisons  or  repellents  are 
used  in  near-by  gardens.  It  feeds  on  practically  all  solanaceous 
plants,  including  eggplant,  tomato,  tobacco,  ground  cherry  (Physa- 
lis),  thorn  apple,  and  Jamestown  weed  (Datura),  henbane  (Hyoscya- 
nitis),  belladonna,  petunia,  and  pepper.  The  last  is  not  often  at- 
tacked, nor  are  the  other  plants  of  different  genera  from  the  potato, 
under  ordinary  circumstances.  Occasionally,  when  none  of  these 
are  to  be  had,  the  insect  will  feed  on  certain  weeds  and  garden  plants, 
among  which  are  cabbage,  thistle,  and  mullein. 

It  was  long  ago  ascertained  that  the  tender-leaved  varieties  of 
potato  are  most  affected,  while  other  kinds,  with  less  tender  foliage, 
such  as  Peach  Blow  and  Early  Rose,  are  comparatively  immune,  more 
particularly  when  growing  in  the  same  field  with  the  preferred 
variety.  Even  eggplant  seems  to  be  preferred  to  certain  varieties  of 
potato,  and  is  consequently  damaged  at  times,  and  tomatoes  are  sub- 
ject to  injury  when  the  foliage  of  potato  is  not  available. 

GENERATIONS. 

The  normal  number  of  generations  of  the  Colorado  potato  beetle 
is  evidently  two.  In  fact  Tower"  ha>  observed  that  this  number 
in  both  temperate  and  tropical  latitudes  is  a  remarkably  constant 
generic  character.  In  the  course  of  his  investigations  he  has  not 
been  able  to  get  the  present  species  to  breed  more  than  tw-ice  in 
a  season  without  a  period  of  hibernation  or  aestivation.  Person- 
ally the  writer  has  never  observed  more  than  two  generations  in 
the  District  of  Columbia.  Years  ago,  however,  Piley  made  the 
positive  statement  that  this  species  is  three-brooded  in  Missouri.''  and 
Lugger  has  made  the  same  statement  in  regard  to  its  development  in 
Minnesota.     Dr.  J.  B.  Smith  claims  two  generations  in  New  Jersey, 

«  Loc.  'it.,  p.  243. 

'<  First  Annual  Report  state  Entomologist  Missouri.  is<;<),  p.  107. 

[Cir.  87] 


with  Bometimes  a  third  partial  generation  which  hibernates  in  the 
pupal  condition.  Considering  the  fad  thai  this  specie*  has  invaded 
new  territory  and  does  not  live  an  entirely  natural  life,  having*  an 
abundance  of  food  and  not  being  restricted  to  its  single  normal  plant. 
it  certainly  9eems  possible  thai  a  third  generation  mighl  be  produced 
in  an  exceptionally  warm  and  humid  season,  and  especially  in  the 
in.'  i  southern  localities  where  11  has  becoi stablished. 

Li i  I     in-  P0K1  . 

Hibernation  takes  place  in  the  beetle  stage,  under  the  ground,  some- 
times ic  a  considerable  depth,  the  beetles  having  been  unearthed  from 
a  few  inches  to  several  feel  beneath  the  surface.  A-  a  rule,  however, 
they  <l(>  not  penetrate  deeper  than  s  or  l"  inches.  Exceptionally  the 
beetles  \\  inter  <>\  er  in  rubbish. 

The  beetles  make  their  initial  appearance  quite  early  in  spring,  at 
times  issuing  from  their  hibernating  quarters  soon  after  the  first 
thaw.  Ai  this  season  they  fly  readily  during  the  more  heated  por- 
tions  of  the  warmer  days,  ami  make  aerial  journeys  of  considerable 
extent.  "  In  flight,  the  striped  elytra  air  raised  ami  held  motionless 
from  ilu'  thorax,  while  the  gauzj  wings,  unfolded  ami  vibrating, 
strike  pleasantly  mi  the  eye  a-  the  sun  intensifies  their  rosy  hues." 
These  flights  frequently  take  place  before  there  an'  any  potato  plants 
for  the  insect  to  l'<vl  upon,  -o  thai  a-  soon  as  tin'  leaves  begin  to  push 
their  way  through  the  ground  the  beetles  are  in  readiness  lor  tin' 
feast.     After  a  few  days  of  feeding  the  female-  deposit  their  eggs. 

The  eggs  are  laid  mostly  on  the  under  surface  of  the  leaves,  ami 
they  hatch  in  from  four  day-  to  a  week  or  a  little  later,  according  to 
temperature.  In  from  sixteen  day-  to  three  week-  the  larva'  usually 
attain  maturity.  They  pass  through  four  stages  or  instars,  then 
descend  into  the  earth  and  undergo  transformation  to  pupae  ami  sub- 
sequently to  beetles,  in  cells  which  the  larva?  form  for  the  purpose. 
The  minimum  period  of  the  pupal  stage  observed  at  Washington, 
I).  ('..  in  August,  1906,  in  a  very  high  temperature  with  correspond- 
ing humidity,  was  seven  days.  This  will  be  two  week-  to  a  little 
longer  in  a  lower  temperature.  The  insect  i-  to  be  found  in  prac- 
tically all  -tam-.  and  particularly  a-  hectic-,  during  the  summer 
months  or  as  long  as  any  -olanaceou-  plants  are  available  a-  food. 
It  ha-  been  learned  that  the  eggs  continue  developing  in  the  ovaries 
during  a  period  of  about  thirty-five  or  forty  day-,  and  it  i-  probable 
that  this  species,  in  common  with  some  others,  ha-  the  ability  of 
retaining  the  eggs  until  a  suitable  place  ha-  been  offered  for  their 

•Observed  by  Me>sr-.  A.  A.  Giraalt  ami  A.  II.  Etosenfeld  at  Myrtle,  Ga.,  in 

May  ami  .June.  1!Mm;. 

[Or.  87] 


10 

deposition.  A  single  female  is  said  to  be  capable  of  producing  from 
five  hundred  to  a  thousand  eggs.  Five  hundred  and  twenty-five  were 
observed  by  Giraull  and  Rosenfeld  in  the  ease  of  one  female,  Laid  in 

masses  of  from  9  to  53,  from  May  21  to  June  5. 

The  entire  life  cycle  from  egg  to  adult  may  be  passed  in  about  four 
weeks.  The  beetles  <>f  the  last  generation  issue  early  in  autumn,  feed 
for  another  three  or  four  weeks,  and  then  enter  the  earth  for  hiberna- 
tion. 

NATURAL   ENEMIES. 

Tt  has  already  been   stated   that  atmospheric  condition-,  with  the 
exception  of  extreme  heat  in  its  more  southerly  range,  are  not  espe- 
cially important   factors  in  the  repression  of 
**"k       ~/iftrv      /-**         this   species:   hence   its   fluctuation    in    num- 
Xjk^Sfl&L*/  tier-,    which    is    noticeable    at    least    locally 

every  season,  must  be  accounted  for  by  the 
activity  of  its  insect  enemies,  the  numbers 
of  which  are  legion.  Se\  era!  groups  of  these 
enemies  are  known,  each  of  which  contains, 
a-  a  rule,  many  species.  Among  the  most 
i  m  p  o  r  t  a  n  t  are 
ladybirds."  many 
common  species  of 
w  h  ich,  in  hot  h 
their  larval  and 
adult  stages,  prey  upon  the  potato  beetle, 
destroying  great  numbers  of  its  eggs  and 
young  larvae.  One  of  the  commonest  of 
these  ladybirds  is  illustrated  for  compari- 
son with  the  Colorado  beetle  by  figure  4. 

Several  ground-beetles.''  also  of  predaceous 
habits,  attack  and  devour  the  larva?  of  this 
potato  beetle,  and  of  these  the  so-called  great  Lebia  (Lebia  grandis 
Hentz.  fig.  5)  is  particularly  attached  to  this  species,  following 
it  wherever  it  goes  and  doing  perhaps  more  effective  service  than 
any  single  natural  enemy'  of  which  we  have  knowledge.  Sev- 
eral  soldier-bugs   also   attack   it.  one   of  which,   the   spined   soldier- 

°  The  ladybird  enemies  of  this  species  are:  Goccinella  9-notata  Hbst,  0.  son- 
guinea  r...  Megilla  maculata  DeG.,  Hippodamia  convergent  Guer.,  //.  tS-punc- 
tata  I...  //.  glacialis  Fab..  Anatis  15-punctata  01.  (ocellata),  and  Chilocorus 
bivulnerus  Muls. 

&Carabid  enemies  include  the  great  Lebia  (Lebia  grandis  Hentz),  the  fiery 
ground  beetle  (Calosoma  calidum  Fab.).  Pasimachus  elongatus  Lee.,  Harpalus 
caliginosus  Fab.,  Lebia  atriventris  Say.  and  Brachynus  kansanus  Lee. 


Fig.  4. — A  ladybird  (Hippodamia 
convergent)  which  preys  on  the 
Colorado  potato  beetle.  En- 
larged (author's  illustration). 


Fig.  5. — Libia  grandis,  an  impor- 
tant potato-beetle  enemy.  En- 
larged (Marx.  del.K 


[Cir.  87] 


11 

\m,r,  i.  illustrated  at   figur.    6.     Other  natural  enemies  are  robber 
£  spiders,  and  a  tachina  fly.      This  last  develops  within  the >body 

of    he  potato  beetle  larva  and  has  I n  observed  so  ahundanl    ... 

potato  Eelds  that  its  buz^ng  resembled  tto  noise  made  by  Aeswara 

£*  of  bees.     Wasps  of  pecie    attack  the  larva*,  and  the  rust 

red  social  wasp- has  1 n  n  carrying  the. ;j^>J^ 

Not  infrequently  the  1 tie  i    f I  parti; ,v.   .,  dull,  v . Jlo   is  h 

rounded  mites.    These  are  external  parasites «  and  help: what  >< 

J^udng  their  hosts,     k  species  of  daddy-long-legs  is  also  a  natural 

"Sta  predator,  insects  include  a  tiger  1 tie  (Tetracha  virginica 

I    (andtworove-beetl.  apteatoSq  undQuedt* ■■ 

i«G»t.).     Most  of  the  s, ies  listed  above  have  been  r >rded 

Riley,  bul  manj  have  also  been  observed  independently  by  others, 
and  correspondenta 
,,('  this  Bureau  fre- 
quently call  atten- 
tion to  the  com- 
moner forma 

Thus  far  only  in- 
ged  foes  of  the  po- 
tato beetle  b  a  v  e 
been  discussed,  but 
certain  mammals, 
bird-,  amphibians 
or  batrachians,  and 
reptile-  are  well- 
known  e  n  e  in  ies. 
(  )ne  of  the  ino-t  im- 
portant of  the  birds 
is  the  rose-breasted 

grosbeak,  whose  servi as  an  enemy  of  this  beetie have ^  1*  ' 

appreciated  until  comparatively  recent  times,     rhe  bobwhite  oi  qu 

•  The  soldier-bugs  Include  I-  acuUvent,       !  ''•  """, 

enemies,  as  they  are  naturally  herbivorous. 
t  Proctacanthus  milbertii  Blacq. 
ephorocera  (Lvdelto)  doryphom  Riley. 

,,!.,,,,,,,,,,,,,,,;,,,,,,.,.,,/..  „,//„..  I.-,,  bave  the  same  habit 

,  mosl  abundanl  of  tbes.  poda  omericana  Riley. 

tUobunum  (Phalangiu ton  Say. 

,Thlg  ,,„,,  is  one  of  the  most  Importanl  enemies  ol  an  equal*   deatri] 

species,  the  ehlncb  bug. 

B7] 


■,_T1>. 

Muehenl 


12 

also  does  excellent  service  and  destroys  many.  Other  birds  which  are 
known  to  eat  the  potato  beetle,  on  the  authority  of  the  Biological 
Survey,  are  the  following:  Ruffed  grouse,  nighthawk,  cuckoo,  scarlet 
tanager,  the  wood,  hermit,  and  olive-backed  thrushes,  and  robin. 
The  crow  not  only  picks  beetles  from  the  vines,  but  digs  them  from 
the  earth.  The  cardinal  is  a  well-known  potato-beetle  destroyer,  and 
even  the  English  sparrow  has  been  seen  to  eat  them. 

Domestic  fowls  are  of  some  assistance  in  destroying  this  pest,  and 
of  these  the  duck  early  took  to  this  insect,  which  is  distasteful  to  some 
other  fowls.  For  some  time  after  the  spread  of  the  Colorado  beetle 
to  new  territory  chickens  did  not  attack  it.  presumably  because  it  has, 
in  common  with  many  other  leaf-beetles,  a  nauseous  taste.  For  sev- 
eral }7ears,  indeed,  it  was  believed  to  be  actually  poisonous.  After  a 
time,  however,  chickens  became  better  acquainted  with  this  insect 
and  began  devouring  its  eggs  and  afterwards  the  larvae,  finally  eating 
the  beetles  with  apparent  relish.  Skunks  and  snakes  are  reported  to 
eat  the  beetles,  and  toads  frequently  gorge  on  them. 

METHODS   OF    CONTROL. 

This  species  is  not  a  difficult  one  to  control,  no  other  method  being 
necessary  for  its  destruction  than  the  free  use  of  an  arsenical  or 
mechanical  means.  Before  taking  up  the  remedies  that  may  be  most 
profitably  employed,  it  may  be  well  to  preface  with  the  statement  that 
an  arsenical  liquid  spray  is  preferred,  and  that  dry  arsenicals,  hand- 
picking,  and  jarring  are  practicable  only  on  a  small  scale  where  the 
grower  has  no  spraying  outfit,  and  occasionally  when  infestation  is 
slight  and  limited  to  a  small  area.  Every  market  gardener  should  be 
equipped  with  a  good  spraying  outfit. 

MECHANICAL    METHODS. 

Jarring,  if  employed  early  in  the  season,  is  of  considerable  value. 
It  is  a  time-worn  remedy  and  so  well  known  as  scarcely  to  need 
descrijition.  It  is  customary  in  many  localities  to  gather  the  beetle^ 
and  their  larvae  in  pans  containing  a  little  water  on  which  a  very 
thin  scum  of  kerosene  is  floating.  Large  shallow  milk  pans  are  excel- 
lent for  this  purpose.  At  the  same  time  the  Qgg  masses  should  be 
picked  where  seen.  Numerous  appliances  have  been  invented  and 
some  patented  for  destroying  this  pest,  but  the  arsenicals  are  so 
effective  that  other  remedies  are  really  not  necessary. 

Brushing. — The  susceptibility  of  potato-beetle  larva1  to  extreme 
heat,  as  has  already  been  recounted,  indicates  that  a  remedy  much  in 
vogue  against  the  asparagus  beetle,  namely,  the  mere  brushing  of  the 
larvae  from  the  plants  on  an  extremely  hot  and  dry  day.  will  be  effect  - 

[Cir.  87] 


L3 

ive.    So  far  as  the  writer  knows,  however,  this  has  never  been  gi 
a  thorough  trial  for  the  potato  beetle.     It  should  l><-  tested. 

/•',///  and  spring  plowing  are  of  value  in  o  general  way,  as  foi 
other  insecta  which  pass  the  winter  in  the  earth,  bul  they  are  bj 
no  means  perfect  measures,  n-  the  beetles  are  hardy  and  nol  much 
affected  by  this  treatment. 

\i:-i  \  ii  ALB. 

Arsenicals  are  the  best  remedies  for  the  Colorado  |><>i;it<>  beetle, 
and  on  small  potato  patches  Paris  ■_■  usually  applied  dry.  mixed 

with  Hour:  but,  as  previously  stated,  it  is  bes(  used  as  :i  Bpray. 
Where  early  hand  methods  have  been  employed,  thorough  treatment 
w  ith  an  arsenical  should  follow . 

Paris  green,  dry.  When  applied  dry,  I'mh  green  is  mixed  with 
from  10  to  20  parts  of  cheap  dry  flour,  sifted  land  pla  ter,  or  fresh 
air-slaked  lime.  This  remedy  affords  best  results  early  in  the  sea 
-dii  mi  young  plants.  It  should  be  dusted  on  preferably  when  the 
dew  is  on  and  by  means  of  powder  guns  or  bellows,  or  the  so-called 
••  dust-spray  '"  machines,  so  as  t<>  cover  the  plants  and  leave  as  little 
surface  as  possible  for  food  for  the  first-appearing  beetles.  In  spite 
of  this,  however,  some  beetles  will  succeed  in  depositing  their  eggs  <>n 
the  lower  surface,  which  is  difficult  to  reach  with  ;t  dry  mixture,  and 
when  the  larvae  hutch  another  application  must  be  made.  In  fad  this 
remedy  must  be  ummI  for  some  time  or  until  the  plants  obtain  ;i  fair 
growth,  when  spraying  will  be  found  more  effective. 

/'/(/  Paris  green  spray  is  prepared  by  mixing  the  arsenical  with 
water  or  Bordeaux  mixture"  at  the  rate  of  1  pound  of  poison  to  75 
to  !•_'">  gallons  of  the  diluent.  It"  water  alone  is  used,  quicklime 
in  aboul  the  same  proportion  a-  the  poison  should  be  added  to 
prevent  scorching.  For  the  proper  mixing  and  application  of  thi- 
spray  a  bucket  pump  or  knapsack  sprayer  of  good  quality  i-  -u tli- 
eient  for  nse  in  small  gardens,  l»ut  on  a  larger  scale  a  potato  sprayer 
to  be  drawn  by  one  or  two  horses  through  the  rows  <d"  plant-  is 
necessary.  With  the  latter,  from  two  to  six  rows  can  be  treated  at 
;•  time.  Special  four  and  -;\  row  potato  sprayers  are  on  the  market. 
The  Paris  green  should  l>e  mixed  with  a  small  quantity  of  water  into 
a  thin  paste  before  the  hulk  of  water  i-  added  and  should  then  lie 
thoroughly  blended  by  churning  in  the  force  pump  or  sprayer.  The 
mixture,  being  a  mechanical  one,  i-  not  constant,  and  the  Pari-  green 
.  will  sink  to  the  bottom.  To  avoid  this  it  must  be  stirred  constantly 
while  being  applied.  It  i-  advisable  to  use  the  Bordeaux  mixture 
diluent,  as  this  is  a  valuable  insect  repellent  a-  well  a-  a  standard 

rectlons  for  the  preparation  of  tlii-  I  and  the  arsenicals  here  >!i-- 

cussed  are  given  in  Fanners'  Bulletin  127,  t".  8.  Department  of  Agriculture, 
which  can  lie  obtained  en  applicatl 

[CIr.  ^71 


14 

fungicide,  and  it  operates  also  against  different  forms  of  blight  and 
other  diseases  which  may  threaten  the  crop. 

Arsenate  of  lead  serves  the  same  purpose  as  Paris  green,  and  for 
use  against  the  Colorado  potato  beetle  i<  still  more  valuable.  Com- 
plaints have  been  made  that  several  applications  of  Paris  green  are 
necessary  during  the  season,  and  extra  doses  are  required  after  each 
rain.  Arsenate  of  lead  is  applied  in  practically  the  same  manner  as 
Paris  green,  but  it  contains  less  poisonous  arsenical  ((>0  to  70  per 
cent  when  dry),  and  being  sold  usually  in  the  form  of  a  paste  it 
is  used  at  a  considerably  greater  strength — i.  e.,  about  1  pound  com- 
bined with  15  to  2f>  gallons  of  water  or  Bordeaux  mixture.  Being 
more  adhesive,  it  adheres  more  firmly  to  the  leafage  and  is  much  less 
likely  to  produce  scorching."  Its  adhesiveness  is  still  more  enhanced 
by  the  addition  of  about  the  same  amount,  by  weight,  of  resin  fish-oil 
soap  as  of  the  arsenical  used. 

The  number  of  sprayings  to  be  applied  will  depend  somewhat  upon 
local  and  seasonal  conditions.  Two  or  three  will  ordinarily  suffice 
for  the  spring  brood,  especially  if  applied  just  after  the  eggs  have 
hatched,  and  the  same  number  should  be  applied  for  the  second 
generation. 

Other  arsenicals  may  be  used  if  preferred.  Among  these  are  ar- 
senite  of  lime  with  soda,  which  has  the  merit  of  being  as  efficient  as 
Paris  green  and  lime  and  far  cheaper.  It  is  not  on  sale  at  the  present 
time  ready  made,  like  arsenate  of  lead.  Scheele's  green,  similar  to 
Paris  green,  is  employed  in  the  same  way  as  the  latter. 

Summary. — To  sum  up  the  directions  for  the  use  of  arsenicals.  it 
should  be  said  that  arsenate  of  lead,  because  it  can  be  purchased 
already  combined,  in  paste  form,  which  is  preferable,  takes  first  place. 
in  the  writer's  opinion,  as  a  potato-beetle  insecticide.  The  mixture  of 
Paris  green,  lime,  and  water  is  in  nearly  the  same  class,  because  the 
ingredients  can  be  purchased  anywhere.  The  dry  Paris  green  mixed 
with  air-slaked  lime  projierly  comes  hist,  as  it  is  less  effective  than 
the  other  mixtures  and  much  of  the  material  is  wasted. 

Precautions  to  -pre rent  poisoning. — In  the  use  of  arsenicals,  as  well 
as  other  poisons,  care  should  always  be  taken  to  avoid  accident.  This 
can  be  best  accomplished  by  plainly  marking  the  contents  on  all 
receptacles,  such  as  bottles  Or  packages,  in  which  the  poison  is  kept. 
In  addition  a  "  POISON  "  label,  which  can  be  obtained  of  any  drug- 
gist, should  be  affixed.  It  is  best  also  to  keep  such  substances  under 
lock  and  key.  The  utensils  employed  in  the  preparation  of  the  mix- 
tures which  have  been  discussed  should  be  thoroughly  cleaned  after 
use. 

a  In  point  of  fact  it  can  be  used  at  the  rate  of  1  pound  to  10  gallons  without 
injury,  but  this  proportion  is  not  advisable,  owing  to  the  extra  cost,  and  scorch- 
ing would  be  apt  to  follow  its  use  on  plants  exposed  to  hot  sunlight. 
[Clr.  87] 


1.-, 

I  I:  \i«k   ITION    "i     wiin-     \\li   i  00P1  RATION. 

It  i-  always  wisdom  on  the  pari  i>t'  the  agriculturist  to  kf»-j >  down 
the  weeds  <>n  the  farm,  and  in  the  treatmenl  of  the  presen(  iii— *-«-t  if 

those   weed-   which    air   kimun   to    fin  nidi    ll    Willi    food,  such   as   -.1 1 1<  1 

bur  and  Jamestown  weed,  were  cut  j 1 1 ~ t  before  seeding,  it  would  pre 
\ tin  the  overdevelopment  of  the  pest  and  of  other  insects  which  feed 
on  the  weeds,  as  well  as  the  weeds  themselves.  The  fanner  should 
familiarize  himself  with  the  wild  food  plants  of  this  pest. 

Keeping  the  potato  patch  and,  in  fact,  the  entire  farm  as  free  as 
possible  from  solanaceous  weeds  should  be  practiced  by  all  farmers  of 
a  neighborhood,  and  if  the  potato  grower  could  secure  the  cooperation 
of  In-  neighbors  in  the  use  of  an  arsenical  spray,  and  would  also  de- 
stroy the  insects  by  spraying  infested  wild  fund  plant-,  the  effect 
would  soon  be  noticeable,  as  there  ran  be  no  doubt  thai  the  3pecies 
would  soon  be  reduced  to  small  numbers,  at  l<'a-t  in  limited  areas,  it' 
this  cooperation  were  thorough  and  persistent.  This  statement  is 
based  on  the  fact  thai  the  beetles  are  seldom  if  ever  seen  migrating 
nowaday-  in  any  such  numbers  a-  in  earlier  years,  and  there  is  not 
therefore  the  constant  danger  of  reinfestation  from  a  distance  a-  was 
formerly  tin-  case.     There  may,  of  course,  be  occasional  exceptions. 

Finally,  a-  a  general  proposition,  tin-  potato  grower  should  keep 
bis  potatoes  free  from  diseases,  such  a-  wilt  and  scab,  and  spray 
for  flea-beetles  and  any  other  insects  which  may  be  found  in  addition 

to  the   Colorado   hectic.      lie   should    also   pa\    particular   attention    to 

the  method-  of  growing  best  adapted  for  hi-  location.  Information 
in  regard  to  the  method-  of  potato  culture  i-  furnished  in  Farmers' 
Bulletin  No.  35,  l.  S.  Department  of  Agriculture,  and  potato  dis- 
eases and  their  treatment  are  considered  in  Farmers4  Bulletin  No.  91. 
Both  of  these  publications  can  he  had  on  application  to  the  Secretarj 
of  Agriculture. 

Approved : 

.1  wii  -  Wilson, 

S    ■        '    .       of  .  \iirh  nit  a  . . 

Washington,  D.C.,April  /".  1 

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